Many mining and natural gas exploration/production activities generate water contaminated with significant concentrations of chemicals and impurities, eventually being discharged into surface water as well as sub-surface aquifers.
This seriously negatively impacts the quality of water used for drinking, as well as for other domestic and commercial needs. In many areas, the wastewater from drilling and mining operations have rendered regional water supplies unusable.
Hydro-fracturing is one of those mining and natural gas exploration production activities that generates waste water. The well-drilling process is involves injecting water, along with sand and a mixture of chemicals (known as fracking fluid) under high pressure into a bedrock/shale formation via the well. The method is informally called fracking or sometimes hydro-fracking, and is intended to increase the size and extent of existing bedrock fractures. The process involves pumping water into fractures at pressures exceeding 3000 psi and flow rates exceeding 85 gallons per minute in order to create long fracture sand pack intersecting with natural fractures in the shale thereby creating a flow channel network to the wellbore. The fracture width is typically maintained after the injection by sand, ceramic, or other particulates that prevent the fractures from closing when the injection is stopped. Hydro-fracturing releases the methane gas trapped in the natural fractures or pores of the shale so it can flow up the pipe
The hydro-fracturing process can use a huge volume of water—up to about several million gallons of water per well. A horizontal well with a 4,500 foot lateral bore, for example, uses about 4 to 5 million gallons of water per well. Accordingly, the hydro-fracturing process can draw millions of gallons of freshwater for use as source water, depleting clean water sources and disturbing the habitat of wildlife.
Hydro-fracturing also generates huge quantities of wastewater. Hydro-fracturing fluids which are injected into a well may contain chemicals that can be toxic to humans and wildlife, including chemicals that are known to cause cancer. These include substances such as: diesel fuel, which contains benzene, ethylbenzene, toluene, and xylene. Some of these chemicals, such as benzene, are considered carcinogenic at very low concentrations.
The flowback water, which is the fluid that comes back up after hydro-fracturing, can include the chemicals pumped in plus both non-toxic and toxic substances that may be present in the shale formation.
Because of the potential negative impact to the environment caused by using hydro-fracturing processes, regulatory agencies are considering a ban on the further issuance of permits.
Accordingly, there is a need for greener technology in drilling wells using hydro-fracturing process including, resulting in purified water containing which can be safely returned to environment. There is also a need to generate over 99% pure salt from the wastewater of the hydro-fracturing process, which can be used commercially, thereby lowering the overall cost of the greener technology in drilling wells as described herein, making its use more desirable.